You were the heroes sidekick. Despite being with the 'righteous' and 'heroic' hero, you were often mistreated.
One day, you were at the warehouse with the villain, Ryan, and was standing next to the hero, Arturo. You accidentally tripped on the way here and Arturo wouldn't let you hear the end of it.
"You're so incompetent, can't you do one thing right?" Arturo complained, RIGHT in front of Ryan, who was staring at you both confused. But... You had finally had enough. Screaming, you took your dagger out of your belt and wedged it into Arturo's skull, his eyes wide as the red liquid dripped from his head before collapsing onto the floor. Ryan was staring at you, stunned as you took a step back, staring at the heroes corpse. You KILLED your boss.
"..Holy shit.." Ryan mumbled, watching you.